On Lake Michigan
the C-30 tall rig rates at 168 while the C-310 rates 186 under PHRF. I've only seen one C-310 rate, and that was not close to the 186 sec / mile rating when compared to my earlier C-30T rating of 168. Most of the go-slow equipment that Catalina added to the C-310 (the roller furling main and the non-adjustable solid vang being two big culprits) as well as the beamy stern make her a pig in light air.That's not saying that the C-30 is a greyhound (in light air and chop, she is a bugger to get and to keep moving), but based on my limited experience watching C-310s and more extensive experience racing a C-30T Mk II ('87) (I came in 4th in the '97 C-30 Nationals and won the 2000 Nationals), you can't go too far wrong with a C-30T Mark II as opposed to a C-310.Having said that, in the '87 C-30 Nationals, the two top boats were early Mark I boats with tillers, and in the light winds of that regatta, getting the weight out of the stern by moving the skipper forward seemed to help a lot (in the 2000 Nationals, the wind was blowing stink, and the entire first day everyone sailed with a reef in the main, and the main determinant for winning was being to keep the boat under control).SteveAlchemist C-30T #4764Alchemist C-320 #909Alchemist C-380 #71H